贵州省2014-2017年麻疹病毒分离株血凝素基因特征

Genetic characteristics of measles virus hemagglutinin in isolates from Guizhou province, 2014-2017

目的分析贵州省2014—2017年麻疹病毒分离株的血凝素(Hemagglutinin,H)基因特征。方法采集贵州省2014—2017年疑似麻疹病例的咽拭子标本,采用Vero/SLAM细胞分离麻疹病毒,提取病毒核酸,经RT—PCR方法扩增麻疹病毒H基因全序列,对序列测定、拼接,分析基因特征。结果共获得83株H基因全序列的麻疹病毒分离株,均为H1a基因型,且有2个明显分支(Cluster A和Cluster B)。分离株H基因之间核苷酸和氨基酸同源性分别为97.8%-100%和98.0%-100%;与H1a基因型参考株(China93—4)的核苷酸和氨基酸同源性分别为98.6%-98.9%和98.2%-98.7%;与中国疫苗株(S191)的核苷酸和氨基酸同源性分别为94.1%-94.5%和94.5%-95.2%。分离株均在第240氨基酸位点由丝氨酸变异为天冬酰胺(S—N),第243氨基酸位点由精氨酸变异为甘氨酸(R—G),处于Cluster A簇中的病毒株第397氨基酸位点由脯氨酸变异为亮氨酸(P—L)。结论贵州省2014—2017年麻疹病毒优势流行株为H1a基因型,且不同病毒传播链持续循环;麻疹病毒H蛋白基因的主要氨基酸位点未发生变异。

Objective To analyze genetic characteristics of hemagglutinin(H) genes of measles virus isolated in Guizhou province during 2014-2017. Methods We collected throat swab samples from suspected measles cases in Guizhou during 2014-2017 to isolate measles viruses by Vero/SLAM cell culture, extract virus RNA, and amplify sequences of H genes by RT-PCR for analysis of genetic characteristics. Results A total of 83 measles virus strains with entire sequences of H genes were obtained; all isolated strains were H1 a genotype and located in two obvious branches(Cluster A and Cluster B). The nucleotide and amino acid homologies of H genes within the isolates were 97.8%-100% and 98.0%-100%, respectively. The nucleotide and amino acid homologies of H genes between the isolates and H1 a genotype reference strain(China93-4) were 98.6%-98.9% and 98.2%-98.7%, respectively, and between the isolates and Chinese vaccine strain(S191) were 94.1%-94.5% and 94.5%-95.2%, respectively. All isolates showed amino acid mutations of S240 N and R243 G, with an amino acid mutation of P397 L for isolates in Cluster A. Conclusions The H1 a genotype was the predominant genotype in Guizhou during 2014-2017, with different virus chains circulating and no mutations at the main amino acid sites of H genes.